Multiple emulsions consist of droplets that encapsulate layers of oil and water from the continuous phase. An active ingredient can be sequestered inside the inner droplets and subsequently released. The layering inside the droplets allows for the release of active ingredients in consecutive steps over long periods of time. Control over the internal structure makes multiple emulsions much sought after in the pharmaceutical, cosmetic and food industries. These emulsions offer versatile templates for structured and patchy colloids, particles of programmable shape, self-assembly tools and biomaterials. Using PDMS microfluidics with multiple channels or glass capillaries with combined flows allows one to mechanically construct high order multiple emulsions. In addition, the use of single surfactants that can stabilise both oil-in-water and water-in-oil layers simplifies their synthesis. These techniques are unsuitable for large-scale production because the number and size of the inner layers are determined by microfluidic flows.